1. Filed of the Invention.
The present invention relates to a device for detecting the presence of a user in order to allow and/or prevent access to the inside of a motor vehicle.
2. Description of the Related Art.
Such detecting devices are already used within the scope of an access system called a hands-free system in order to automatically trigger the release of the door of a motor vehicle as the user approaches, without the latter needing to use a key or a remote control. To carry out this automatic unlocking before opening the door, detection of the user is used to activate a remote exchange of data between an on-board recognition device on the vehicle and an identifier worn by the user. When the identifier is recognized as correct by the recognition device, the lock is released, thus allowing the user to open the opening leaf of the vehicle by grasping the handle. These known detecting devices are generally incorporated into the handles of the opening leaves of a vehicle since the detecting action takes place prior to opening the opening leaf. Thus, it is known, in particular from document U.S. Pat. No. 6,075,294, to place the detecting electrode of a presence sensor in a handle.
However, in some cases, it may be desirable to incorporate a presence detecting device directly into the bodywork of the vehicle. Thus, for example, document FR 2 740 501 teaches the use of a presence sensor in the rear of the motor vehicle around the trunk.
However, such a device requires fastening an additional casing containing the presence sensor to the bodywork.
One aim of the present invention is to provide a detecting device which can be placed in a preexisting decorative element on the vehicle.
This aim is achieved by the fact that the decorative element has at least one electrically conducting part coupled at least partially to the detecting electrode so as to form an active detecting surface. Thus, by virtue of the present invention, this device does not require an extra part to be added and fastened to the bodywork. This results in a substantial reduction in the cost price of the detecting device.
According to a first embodiment of the present invention, the electrically conducting part is coincident with the detecting electrode.
According to a second embodiment of the present invention, the electrically conducting part comprises, on the one hand, the detecting electrode and, on the other hand, a surface layer forming an offset electrode. In addition, an insulating part is inserted between the detecting electrode and the false electrode so as to form a capacitor.
Thus, advantageously, this capacitor protects the treatment circuit against electrical overload.
According to a third embodiment of the present invention, the decorative element has a tongue and is completely covered with a surface layer forming an offset electrode. The electrically conducting part comprises, on the one hand, the detecting electrode and, on the other hand, the offset electrode. A second insulating part is inserted between the detecting electrode and the offset electrode in order to form a capacitor. Thus, the detecting electrode and the electronic processing circuit are placed inside the vehicle so that the electrical wire connecting the electrical components of the detecting device is inaccessible from outside the vehicle. Consequently, the risk of theft of the vehicle by creating a short circuit in the electrical system is significantly decreased.
Advantageously, the device according to the present invention has the following features:                the offset electrode is formed by a layer of electrically conducting paint.        the capacitor has a capacitance of around ten picofarads.        the insulating part comprises a layer of plastic or of rubber.        the electrically conducting part is electrically insulated from the bodywork by a first insulating part.        the thickness of the first insulating part is greater than about 1 mm.        a closed housing, sheltered from water, is made in the first insulating part and designed to accommodate the electronic processing circuit. Thus, advantageously, it is not necessary to fasten an extra casing containing the processing electronics to the bodywork.        the detecting device is formed by a touch-sensitive capacitive sensor such that the decorative element forms a clearly defined touch-sensitive surface. Thus, by virtue of this device, the user easily identifies the region for controlling the locking/unlocking of the locks and/or the opening/closing of the doors.        the decorative element is in the form of a logo representing the make of the vehicle manufacturer, the model of the vehicle and/or the identity of the manufacturer. Thus this device has an esthetic appearance.        the detection of a user is confirmed by the emission of a sound and/or light signal.        the opening leaf is a trunk or a rear hatchback.        
Moreover, it has been shown that integrating a sensor, consisting of detecting electrodes and an electronic processing circuit, in the bodywork presents many problems and especially that of false detections. These false detections arise, on the one hand, from significant exposure of the sensor to bad weather and, on the other hand, from interference due to the proximity of the sensor electrodes with the metal bodywork of the vehicle. In fact, bad weather (water, snow and other damp elements) causes false detections, which can be detrimental to the proper operation and to the reliability of the device.
A second aim of the invention is therefore to eliminate these drawbacks by providing a touch-sensitive detecting device which can be positioned directly on the vehicle bodywork while at the same time having improved detection reliability.
To this end, according to a variant embodiment of the present invention, the decorative element and/or the detecting electrode has, in cross section, sloping faces promoting the removal of water. Thus, by virtue of this structure, the touch-sensitive detecting device is positioned directly on the vehicle bodywork.
Preferably, the insulating part has at least one part forming a water channel so as to promote the removal of water.
Preferably, the insulating part forms a water channel and is made in the form of a groove made in the layer.
Advantageously, the first layer has an upper thickness of about 1 mm.
The touch-sensitive detecting device is advantageously used, within the scope of a hands-free access system, after prior identification of the user, in order to control functions:                of locking and/or of unlocking the opening leaves of the vehicle, after prior identification of the user, in the case of a hands-free access system,        of opening and/or of closing especially for the trunk.        
Other features and advantages of the invention will become further apparent from the following detailed description. This description, which is purely illustrative and nonlimiting, relates to the exemplary embodiments described with reference to the appended figures, among which: